Quartz glass crucible for pulling single-crystal silicon and process for producing single-crystal silicon

ABSTRACT

The invention provides a quartz glass crucible for pulling up single-crystal silicon, and a method for producing single-crystal silicon by using it. The quartz glass crucible is characterized by having a crystallization promoter-containing layer as the inner surface thereof and is characterized in that, when single-crystal silicon is pulled up, macular crystallized regions are formed in the inner surface thereof by the action of the crystallization promoter. In the quartz glass crucible, a crystallized substance is not generated sparsely in the inner surface thereof and therefore does not shed off; outgassing holes are not generated through micro-peeling off of a part of the crystal layer formed in the inner surface thereof, unlike in a case where a crystal layer is formed entirely in the inner surface thereof; molten silicon does not penetrate into the area between the crystal layer and the underlying glass layer through the outgassing holes formed by micro-peeling off; and therefore the quartz glass crucible brings about a high yield.

TECHNICAL FIELD

The present invention relates to a quartz glass crucible to be used inproducing single-crystal silicon for use for substrates for solar cells,semiconductor devices, etc., and to a method for producingsingle-crystal silicon by using it.

BACKGROUND ART

Single-crystal silicon is produced from polycrystalline siliconaccording to an FZ method or a CZ method. In particular, at present,single-crystal silicon produced according to a CZ method takes a marketshare of at least 70%. In the CZ method, polycrystalline silicon is putinto a quartz glass crucible, melted under heat therein, andsingle-crystal silicon is pulled up by the use of a seed crystal.

The quartz glass crucible is, as only one member that is kept in contactwith molten silicon, an important member that determines the yield andthe quality of single-crystal silicon. The yield of single-crystalsilicon is lowered when the crystallized substance (FIG. 4) having asize of φ2 to φ6, which is generated through reaction of molten siliconand a quartz glass crucible at high temperature and sparsely exists inthe interface therebetween, peels off from the inner surface of thequartz glass crucible and adheres to the edges of single-crystal siliconfor polycrystallization. Accordingly, uniform crystallization of theentire inner surface of the quartz glass crucible is now underinvestigation.

For example, Patent Reference 1 discloses a method of applyinghigh-concentration barium onto the entire inner surface of a quartzglass crucible to thereby crystallize the inner surface of the quartzglass crucible entirely into a thick crystal layer before use.

Patent Reference 2 discloses a method of increasing the pulling yield ofsingle-crystal silicon by using the crucible of Patent Reference 1.

However, in the methods described in Patent References 1 and 2,relatively high-concentration barium coating is needed, in which,therefore, there may occur a problem in that barium mixing into thegrowing silicon crystal may form defects. Further, in case oflarge-diameter silicon crystal growth, severer heat environments areneeded, and therefore the thickly-crystallized quartz glass crucible maybe significantly deteriorated. In addition, use of high-concentrationbarium makes it difficult to handle the crucible.

Patent Reference 3 discloses a method of forming a coating film or asolid solution layer of a crystallization promoter within a depth of 1mm of the inner surface of a quartz glass crucible, thereby enhancingthe durability of the crucible. In case where a 2a Group elementcompound is used as the crystallization promoter, its solution isapplied onto the inner surface of a crucible and dried to form a coatingfilm thereon. On the other hand, in case where a 3b Group elementcompound is used as the crystallization promoter, a powder doped with itis scattered during melting to form a solid solution layer.

In these methods, however, the concentration of the crystallizationpromoter is too high, and therefore the crystal layer readily separatesand peels off from the inner surface of the quartz glass crucible, andit is difficult to increase the yield in pulling up single-crystalsilicon.

Patent Reference 4 discloses a quartz glass crucible, of which thecrystallization promoter-containing layer of the inner surface hardlypeels off, and which has high crucible strength at high temperature andcan stably attain single-crystal silicon pulling.

However, for maintaining the high strength of the quartz glass crucibleduring pulling, the crystallization promoter-containing layer must bethick to be from 1 to 2 mm, and quartz powder in which the concentrationof the crystallization promoter is gradually increased must be stepwisedeposited to form multiple layers, and therefore it could not be saidthat the layer formation efficiency is good.

In addition, in this method, in case where the crystallization promoterhas a low concentration and is used at low temperature for smalldiameter quartz glass crucibles, the crystallization speed is low andthe crystallized substance generated in the inner surface of the quartzglass crucible may peel off and therefore it is difficult to stablyincrease the yield in pulling up single-crystal silicon.

-   [Patent Reference 1] JP-A 9-110590-   [Patent Reference 2] JP-A 9-110579-   [Patent Reference 3] JP-A 8-002932-   [Patent Reference 4] JP-A 2007-001806

DISCLOSURE OF THE INVENTION Problems that the Invention is to Solve

In the above-mentioned prior-art techniques, for preventing thecrystallized substance (FIG. 4) having a size of from φ2 to φ6 andgenerated sparsely in the inner surface of a quartz glass crucible, fromshedding and dropping down, uniform crystallization of the inner surfaceis emphasized, but any effective solution is not proposed therein forpreventing the excessively crystallized crystal layer from shedding offfrom the inner surface of the quartz glass crucible. Specifically, thepresent inventors' investigations have revealed that, in case where acrystal layer is formed entirely in the inner surface of a quartz glasscrucible, the gases, for example, SiO, air in bubbles, gaseousimpurities and the like existing inside the quartz glass crucibleexpanded at high temperature during pulling of single-crystal siliconwould lose their escape route owing to the crystal layer formed byuniformly crystallizing the entire inner surface of the quartz glasscrucible and, as a result, a large number of outgassing holes having asize of a few tens μm that are for discharging the gases existing insidethe crucible are formed through micro-peeling off of a part of thecrystal layer (FIG. 5, FIG. 6). Consequently, molten silicon maypenetrate into the area between the crystal layer and the underlyingglass layer (transparent layer or opaque layer) through the outgassingholes formed by micro-peeling off (FIG. 7, FIG. 8), thereby bringingabout shedding of the crystal layer.

On the other hand, when the degree of crystallization is lowered due tofears of shedding of the crystal layer from the inner surface of thequartz glass crucible, then it may be impossible to prevent thecrystallized substance having a size of from φ2 to φ6 and generatedsparsely in the inner surface of the quartz glass crucible, fromshedding and dropping down,

The present invention has been made in consideration of theabove-mentioned situation, and its object is to provide a quartz glasscrucible, in which a crystallized substance is not generated sparsely inthe inner surface thereof and therefore does not shed and drop down, inwhich outgassing holes are not generated through micro-peeling off of apart of the crystal layer formed in the inner surface thereof, unlike ina case where a crystal layer is formed entirely in the inner surfacethereof, in which molten silicon does not penetrate into the areabetween the crystal layer and the underlying glass layer through theoutgassing holes formed by micro-peeling off, and which therefore bringsabout a high yield, and to provide a method for producing single-crystalsilicon by using the crucible.

Means for Solving the Problems

For solving the above-mentioned problems, the invention is characterizedby the following:

First: A quartz glass crucible for pulling up single-crystal silicon,characterized by having a crystallization promoter-containing layer asthe inner surface thereof and characterized in that, when single-crystalsilicon is pulled up, macular crystallized regions are formed in theinner surface thereof by the action of the crystallization promoter.Second: The quartz glass crucible of the above first, wherein themacular crystallized regions are formed through continuous bonding ofthe crystallized substance sparsely generated in the inner surface ofthe quartz glass crucible during pulling of single-crystal silicon.Third: The quartz glass crucible of the above first or second, whereinthe macular crystallized regions include unit regions each having anindependent form as the marginal part thereof is substantially closedand the area of the form falls within a range of from 10 to 100 mm².Fourth: The quartz glass crucible of the above third, wherein at least apart of the unit regions of the macular crystallized regions are furtherbonded continuously to each other, and the total area of the macularcrystallized regions accounts for from 30 to 80% of the inner surface ofthe quartz glass crucible.Fifth: The quartz glass crucible of the above fourth, wherein in themacular crystallized regions, microholes of from 10 to 100 μm in sizeare not generated during pulling of single-crystal silicon.Sixth: The quartz glass crucible of any of the above first to fifth,wherein the crystallization promoter is at least one 2a Group elementselected from magnesium, strontium, calcium and barium.Seventh: The quartz glass crucible of any of the above first to sixth,wherein the crystallization promoter is barium, and the crystallizationpromoter-containing layer is formed by applying a barium-coatedhigh-purity silica powder onto the inner surface of the quartz glasscrucible and melting it thereon.Eighth: The quartz glass crucible of the above seventh, wherein thecrystallization promoter-containing layer has a thickness of from 30 to200 μm.Ninth: The quartz glass crucible of the above seventh or eighth, whereinthe crystallization promoter-containing layer has a barium concentrationof from 100 to 200 ppm.Tenth: The quartz glass crucible of any of the above seventh to ninth,wherein the crystallization promoter-containing layer has a bariumconcentration of from 130 to 170 ppm.Eleventh: A method for producing single-crystal silicon by using thequartz glass crucible of any of the above first to tenth, characterizedby comprising a step of putting polycrystalline silicon into the quartzglass crucible, a step of heating and melting the polycrystallinesilicon to form a molten silicon liquid, and a step of pulling upsingle-crystal silicon from the molten silicon liquid in the quartzglass crucible by using a seed crystal.

Advantage of the Invention

According to the invention, during pulling of single crystal, acrystallized substance is not sparsely generated in the inner surface ofthe quartz glass crucible, and macular crystallized regions of acrystallized substance continuously bonding to each other are formedtherein. In that manner, macular crystallized regions are formed andtherefore, the crystallized substance as sparsely generated in the innersurface of the quartz glass crucible is prevented from shedding off. Inparticular, since the quartz glass crucible has a crystallizationpromoter in the depth direction of the inner surface thereof, thecrystallization of the macular crystallized regions is promoted in thedepth direction of the inner surface. Accordingly, the crystallizedsubstance sparsely generated in the inner surface of the crucible can besignificantly prevented from shedding off.

Further, during pulling of single-crystal silicon, gases existing insidethe quartz glass crucible can be discharged away from the other regionsthan the macular crystallized regions in the inner surface of the quartzglass crucible. Therefore, the crystal layer in the macular crystallizedregions does not micro-peeling off to form outgassing holes, and themolten silicon does not penetrate into the area between crystal layerand the underlying glass layer in the macular crystallized regions.Accordingly, the crystal layer in the macular crystallized region doesnot shed off.

As in the above, a crystallized substance is not sparsely generated inthe inner surface of the quartz glass crucible of the invention to dropoff, unlike before, and a part of the crystallized layer does notmicro-peeling off to form outgassing holes, unlike in a case where acrystal layer is formed entirely in the inner surface thereof, andmolten silicon does not penetrate into the area between the crystallayer and the underlying glass layer through the outgassing holes formedby micro-peeling off. Accordingly, the invention provides the quartzglass crucible capable of pulling up single-crystal silicon at anextremely high yield.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 This is a cross-sectional view schematically showing oneembodiment of a quartz glass crucible for pulling up single-crystalsilicon of the invention.

FIG. 2 This is a view graphically showing the inner surface of a quartzglass crucible with macular crystallized regions formed therein.

FIG. 3 This is a photograph of the inner surface of a quartz glasscrucible of Example with macular crystallized regions formed thereinafter pulling up of single-crystal silicon by the use of the quartzglass crucible.

FIG. 4 This is a photograph of a crystallized substance having a size offrom φ2 to φ6 generated in the inner surface of a quartz glass crucibleof Comparative Example.

FIG. 5 This is a photograph of outgassing holes of a few tens μm in sizegenerated in the crystallized layer surface of the inner surface of aquartz glass crucible of Comparative Example.

FIG. 6 This is an electromicroscopic photograph of outgassing holes of afew tens μm in size generated in the crystallized layer surface of theinner surface of a quartz glass crucible of Comparative Example.

FIG. 7 This is a photograph showing a condition where molten silicon hasflowed into the area beneath the crystallized layer through outgassingholes of about 10 μm in size generated in a quartz glass crucible ofComparative Example.

FIG. 8 This is a photograph showing a condition where molten silicon hasflowed into the area beneath the crystallized layer and the opaque layerof quartz glass and the crystallized layer has peeled off from theopaque layer of quartz glass, as generated in a quartz glass crucible ofComparative Example.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

-   -   1 Quartz Glass Crucible    -   2 Opaque Layer of Quartz Glass    -   3 Transparent Layer of Quartz Glass    -   4 Crystallization Promoter-Containing Layer    -   5 Macular Crystallization Region    -   5 a Unit Region    -   6 Outgassing Hole    -   7 Silicon    -   8 Surface of Crystal Layer    -   9 Crystal Layer    -   10 Silicon    -   11 Opaque Layer of Quartz Glass    -   12 Region except Macular Crystallization Region

BEST MODE FOR CARRYING OUT THE INVENTION

The invention is described in detail hereinunder.

FIG. 1 is a cross-sectional view schematically showing one embodiment ofa quartz glass crucible for pulling up single-crystal silicon of theinvention. As illustrated in the drawing, the quartz glass crucible 1 ofthe invention has a crystallization promoter-containing layer 4 as theinner surface thereof.

The crystallization promoter to be contained in the crystallizationpromoter-containing layer in the invention is one that promotes, inpulling up of single-crystal silicon, the reaction of the inner surfaceof the quartz glass crucible and a high-temperature molten siliconliquid and the formation of a crystallized substance in the interfacetherebetween; and its specific examples include Group 2a elements ofmagnesium, strontium, calcium, barium, etc. One or more of these may beused here either singly or as combined.

Of those crystallization promoters, barium has a small segregationcoefficient and therefore has an excellent characteristic that it ishardly taken in the single-crystal silicon in pulling it up; andaccordingly, use of barium as the crystallization promoter in theinvention is especially preferred.

One characteristic feature of the invention is that, during pulling upof single-crystal silicon, macular crystallized regions are formed inthe inner surface of the crucible by the action of the crystallizationpromoter.

In this, the macular crystallized regions are described with referenceto the graphic view of FIG. 2 and the photograph of FIG. 3. In FIG. 2and FIG. 3, the reference numeral 5 is the macular crystallized region.

The macular crystallized region is formed through continuous bonding ofthe crystallized substance generated sparsely in the inner surface ofthe quartz glass crucible in pulling up of single-crystal silicon, andthis definitely differs from heretofore-known sparsely-generatedcrystallized substances in point of the form and the size thereof.

Specifically, the sparsely-generated crystallized substance is typicallya circular one having a size of from φ2 to φ6, as shown in FIG. 4, andas compared with those of the macular crystallized region in theinvention, the form and the size thereof each are within a given regionand have a given regularity. Most of the sparsely-generated crystallizedsubstances have an area of less than 10 mm².

As opposed to this, the macular crystallized region in the invention hasan irregular and nonuniform outward appearance as a whole. Asgraphically shown in FIG. 2, the macular crystallized region 5 includesa unit region 5 a having an independent form as the marginal partthereof is substantially closed, such as typically one surrounded by thedotted-line oval in the drawing.

As shown in the photograph of FIG. 3, the macular crystallized regionsare irregular and nonuniform; and as shown in FIG. 2 as one examplethereof, the regions include a plurality of unit regions 5 a, such asunit region 5 a ₁, unit region 5 a ₂, unit region 5 a ₃, etc., ascontinuously communicating with each other via a thin part therebetween;however, as a matter of visual convenience, the unit region 5 a can beso understood that it can be recognized as an independent form that isformed by substantially closing the marginal part thereof.

The unit region is formed as a result of reaction of a high-temperaturemolten silicon liquid with the inner surface of the quartz glasscrucible in pulling up of single-crystal silicon, followed by continuousbonding of the crystallized substance generated in the interface throughthe reaction, by the action of the crystallization promoter contained inthe inner surface of the quartz glass crucible. Specifically, theabove-mentioned circular crystallized substances of from φ2 to φ6 insize are continuously bonded to each other to expand the unit region,and the unit region is therefore obviously larger than the size of thecrystallized substance. The unit region typically includes one having anarea falling within a range of from 10 to 100 mm². The unit region mayinclude any others each having an area of more than 100 mm².

By continuously bonding the crystallized substance in the inner surfaceof the quartz glass crucible to form nonuniform macular crystallizedregions, and further by making a crystallization promoter exist in thedepth direction of the inner surface of the quartz glass crucible, thecrystallization in the inner surface of the quartz glass crucible may bethereby promoted in the depth direction and the crystallized substancegenerated in the inner surface can be thereby prevented from sheddingoff. Forming the nonuniform macular crystallized regions in the innersurface of the quartz glass crucible makes it possible to discharge thegases existing inside the quartz glass crucible, through the otherregion 12 than the macular crystallized regions in FIG. 2, duringpulling of single-crystal silicon, and therefore the crystal layer inthe macular crystallized regions can be prevented from shedding off fromthe inner surface of the quartz glass crucible.

In one preferred embodiment of the invention, at least a part of theunit regions of the macular crystallized regions, for example, the unitregion 5 a ₁, the unit region 5 a ₂, the unit region 5 a ₃ and the likeshown in FIG. 2, are further bonded continuously to each other, and thetotal area of the macular crystallized regions accounts for from 30 to80%, preferably from 30 to 70% of the inner surface of the quartz glasscrucible.

In case where the total area of the macular crystallized regions is lessthan 30% of the inner surface of the quartz crucible, a large number ofcircular crystallized substances of from φ2 to φ6 in size may exist inthe inner surface and they may frequently shed off in pulling ofsingle-crystal silicon, whereby the single crystal pulling yield maylower.

On the other hand, when the total area of the macular crystallizedregions is more than 80% of the inner surface of the quartz crucible,then the gases existing inside the quartz glass crucible and havingexpanded at high temperature could not be fully discharged out, duringpulling of single-crystal silicon. In such a case, the gases maymicro-peel off the crystal layer to form outgassing holes, and the gasesmay be discharged out through the outgassing holes (FIG. 6). In this,the present inventors have confirmed the formation of a large number ofoutgassing microholes of a few tens μm in size in the crystal layer(FIG. 5).

The hot molten silicon put in the quartz glass crucible may flow intothe glass layer (transparent layer or opaque layer around it) of thequartz glass crucible existing below the crystal layer, through theoutgassing microholes of a few tens μm in size (FIG. 7), and the glasslayer is melted by the high-temperature molten silicon, and as a result,the molten silicon penetrates into the area between the crystal layerand the glass layer and the crystal layer sheds away from the quartzglass crucible (FIG. 8).

In one preferred embodiment of the invention, the crystallizationpromoter is barium, and the crystallization promoter-containing layer isformed by applying a barium-coated high-purity silica powder onto theinner surface of the quartz crystal crucible and melting it thereon.Thus formed, the thickness of the crystallization promoter-containinglayer is preferably from 30 to 200 μm. When barium is contained withinthe thickness range and when the crystallization is promoted in thedepth direction of the inner surface of the quartz glass crucible, thenthe crystallized substances generated in the inner surface can beprevented from shedding off.

In case where the crystallization promoter is contained in the depth ofless than 30 μm from the inner surface, the crystallization could not bepromoted when the crystallization promoter is contained in a highconcentration therein, like in the case where the agent is applied ontothe inner surface, and therefore crystallized substances generated inthe inner surface would shed off.

In case where the crystallization promoter is contained in the depth ofmore than 200 μm from the inner surface, the crystallization may bepromoted and the inner surface of the quartz glass crucible may beentirely crystallized, and if so, nonuniform macular regions could notbe formed. Accordingly, the crystal layer sheds off from the innersurface of the quartz glass crucible.

Regarding the crystallization promoter content, the barium concentrationis preferably from 100 to 200 ppm, more preferably from 130 to 170 ppm.

When the barium concentration is less than 100 ppm, then theconcentration of barium as the crystallization promoter is low andtherefore the crystallization could not be promoted, and thecrystallized substances generated in the inner surface of the quartzglass crucible may shed off.

When the barium concentration is more than 200 ppm, then thecrystallization may be promoted too much and the entire inner surface ofthe quartz glass crucible may be crystallized so that macularcrystallized regions could not be formed. In such a case, the crystallayer may shed off from the inner surface of the quartz glass crucible.

On the other hand, when the barium concentration in the crystallizationpromoter-containing layer is from 130 to 170 ppm, then macularcrystallized regions could be surely formed in a range of from 30 to 80%of the inner surface of the quartz glass crucible. Specifically, of thecondition in pulling of single-crystal silicon, the quantity of heat tobe given to the quartz glass crucible differs depending on the diametersize of the quartz glass crucible, etc. The condition of the macularcrystallized regions in the inner surface of the quartz glass cruciblemay be influenced by the quantity of heat to be given to the quartzglass crucible, and therefore, for surely forming nonuniform macularcrystallized regions in a range of from 30 to 80% of the inner surface,not depending on the condition in pulling of single-crystal silicon,barium must be distributed in the crystallization promoter-containinglayer in a concentration of from 130 to 170 ppm therein. For example, ina case where on the diameter size of the quartz glass crucible is 16inches, macular crystallized regions can be surely formed in a range offrom 30 to 80% of the inner surface when the barium concentration isfrom 130 to 200 ppm. On the other hand, in a case where on the diametersize is 24 inches, macular crystallized regions can be surely formed ina range of from 30 to 80% of the inner surface when the bariumconcentration is from 100 to 170 ppm.

Using the quartz glass crucible of the invention described above, forexample, it is possible to produce a single-crystal silicon ingot thatmay be a base material of a silicon substrate for use in solar cells orsemiconductor devices, according to heretofore-known ordinaryconditions. Specifically, one ordinary production method for asingle-crystal silicon ingot using the quartz glass crucible is asfollows: A necessary amount of polycrystalline silicon is filled in thequartz glass crucible, then the single-crystal silicon pulling device isreplaced with argon gas, and heated up to 1420° C. or higher, forexample, up to from 1500° C. to 1600° C. by a graphite heat generator tomelt the polycrystalline silicon. Then, the temperature is graduallylowered so that the temperature of the surface of the molten liquidcould reach 1420° C., and thereafter a seed crystal (prismatic body offrom 6 to 8 mm in size) is dipped in the molten liquid so that thesurface of the seed crystal is thereby melted. For removing thedislocation having existed in the seed crystal or the dislocation newlygenerated by the thermal shock in seeding, a thin and long neck parthaving a diameter of from 3 to 5 mm and a length of from 100 to 300 mmis formed at a relatively high pulling up speed (1 to 5 mm/min). Withlowering the temperature around the upper surface of the molten liquidin the quartz glass crucible, the pulling up speed is lowered to from0.1 to 0.5 mm/min, whereupon a shoulder part having a drasticallyincreasing diameter is formed from the thin-diameter neck part to theconstant-diameter part thereof having a predetermined diameter within ashort period of time. By controlling the temperature and the pulling upspeed, the constant-diameter part of the crystal is grown so as to havea constant crystal diameter. When the crystal has reached apredetermined length, the temperature is lowered a little and thepulling up speed is increased so as to thin the crystal, whereby thediameter of the crystal is gradually decreased from theconstant-diameter part thereof, and a tail having a diameter of zero isformed. When the single-crystal silicon ingot has separated from themolten liquid, the pulling up operation is finished, and single-crystalsilicon can be produced at a high yield.

EXAMPLES

The invention is described in more detail with reference to thefollowing Examples; however, the invention is not whatsoever restrictedby these Examples.

Examples

A natural quartz powder was put into a rotating mold, then a voltage wasapplied to the graphite electrode, and an opaque layer of a quartz glasscrucible was formed from the inner surface of the mold bycurrent-applying electric arc heating. Subsequently, a natural quartzpowder was gradually diffused and supplied in the arc flame to form atransparent layer. Further continuously, a barium-coated natural quartzpowder, which had been prepared by coating a natural quartz powder witha solution of barium serving as the crystallization promoter in theinvention, was gradually scattered and supplied to form acrystallization promoter-containing layer, and the melting operation wasthus finished. Afterwards, a quartz glass crucible having an opaquequartz glass layer 2 in the outer peripheral part thereof, a transparentquartz glass layer 3 inside it and a crystallization promoter-containinglayer 4 further inside it, as shown in FIG. 1, was produced according toa known process.

With the thickness of the crystallization promoter-containing layervaried in three stages within a range of from 30 to 200 μm, and with thebarium concentration in the crystallization promoter-containing layervaried in four stages within a range of from 100 to 200 ppm, quartzglass crucibles having a diameter size of 16 inches or 24 inches werethus produced.

Thus produced, the quartz glass crucibles having a diameter size of 16inches or 24 inches were tried for pulling of single-crystal silicon,and as a result, macular crystallized regions were formed in the innersurface in pulling. The macular crystallized regions had, as shown inFIG. 2, an irregular and nonuniform appearance as a whole, and includedunit regions having an area of from 10 to 100 mm². At least a part ofthe unit regions of the macular crystallized regions were further bondedcontinuously to each other, and the total area of the macularcrystallized regions accounted for from 30 to 80% of the inner surfaceof the quartz crucible.

In all of the quartz glass crucibles of these Examples, the crystallizedsubstances generated in the inner surface were prevented from sheddingoff, and the crystal layer did not shed off from the inner surface ofthe quartz glass crucible since outgassing holes were not formed, and ahigh single crystal formation yield of 75% or more was attained. Theresults are shown in Table 1.

Comparative Examples

Quartz glass crucibles having a diameter size of 16 inches or 24 incheswere produced in the same manner as in Examples, except that thethickness of the crystallization promoter-containing layer was 10 μm or220 μm and the barium concentration in the crystallizationpromoter-containing layer was 0 ppm, 70 ppm or 230 ppm. The quartz glasscrucibles were tried for pulling of single-crystal silicon. The resultsare shown in Table 1.

When the thickness of the crystallization promoter-containing layer was10 μm and was less than 30 μm, a large number of crystallized substanceshaving a size of from φ2 to φ6, which form in the presence of nocrystallization promoter, formed in the inner surface of the quartzglass crucible, and the crystallized substances shed off from the innersurface of the quartz glass crucible. Accordingly, the single crystalpulling yield could not be increased.

When the thickness of the crystallization promoter-containing layer was220 μm and was more than 200 μm, nearly a whole of more than 80% of theinner surface of the quartz glass crucible crystallized, and a largenumber of outgassing holes, which are small holes of a few tens μm insize, were seen in the surface of the crystal layer, and molten siliconpenetrated into the area between the crystal layer and the opaque layerthrough the outgassing holes (FIG. 7). Accordingly, the single crystalpulling yield could not be increased.

When the diameter size of the quartz glass crucible was 16 inches andthe barium concentration in the crystallization promoter-containinglayer was less than 130 ppm, or when the diameter size of the quartzglass crucible was 24 inches and the barium concentration in thecrystallization promoter-containing layer was less than 100 ppm, a largenumber of crystallized substances having a size of from φ2 to φ6, whichform in the presence of no crystallization promoter, formed in the innersurface of the quartz glass crucible, and the crystallized substancesshed off from the inner surface of the quartz glass crucible.Accordingly, the single crystal pulling yield could not be increased.

When the diameter size of the quartz glass crucible was 16 inches andthe barium concentration in the crystallization promoter-containinglayer was more than 200 ppm, or when the diameter size of the quartzglass crucible was 24 inches and the barium concentration in thecrystallization promoter-containing layer was more than 170 ppm, nearlya whole of more than 80% of the inner surface of the quartz glasscrucible crystallized, and a large number of outgassing holes, which aresmall holes of a few tens μm in size, were seen in the surface of thecrystal layer, and molten silicon penetrated into the area between thecrystal layer and the opaque layer through the outgassing holes (FIG.7). Accordingly, the single crystal pulling yield could not beincreased.

TABLE 1 Crystallization Promoter (barium) Concentration (ppm) 0 70 100130 170 200 230 16 inches Thickness of 10 Δ Δ: a —  Δ: a —  Δ: b —Crystallization 30 —  Δ: a ◯: b ◯: b ◯: b ◯: b Promoter-Containing 100Δ: a  Δ: b ◯: b ◯: b ◯: b ◯: c Layer (μm) 200 — ◯: b ◯: b ◯: b ◯: b  X:c 220 ◯: b  — ◯: b —  X: c — 24 inches Thickness of 10 Δ Δ: a —  Δ: a — Δ: b — Crystallization 30 — ◯: b ◯: b ◯: b ◯: b — Promoter-Containing100 Δ: a ◯: b ◯: b ◯: b ◯: c  X: c Layer (μm) 200 — ◯: b ◯: b ◯: b  X: c— 220 ◯: b  — ◯: b — — — ◯: No crystal layer shedding, single crystalyield 75% or more. Δ: No crystal layer shedding, single crystal yieldless than 75%. X: Outgassing holes (FIG. 4, FIG. 5) confirmed, orcrystal layer partly shed. Single crystal yield less than 75%. Area ofcrystallized region in the inner surface: a from 0 to less than 30%, bfrom 30 to less than 80%, c 80% or more.

1-12. (canceled)
 13. A quartz glass crucible for pulling upsingle-crystal silicon, characterized by having a crystallizationpromoter-containing layer as the inner surface thereof and characterizedin that, when single-crystal silicon is pulled up, macular crystallizedregions, of which the total area accounts for from 30 to 80% of theinner surface of the quartz glass crucible, are formed in the innersurface thereof by the action of the crystallization promoter.
 14. Thequartz glass crucible as claimed in claim 13, wherein the macularcrystallized regions are formed through continuous bonding of thecrystallized substance sparsely generated in the inner surface of thequartz glass crucible during pulling of single-crystal silicon.
 15. Thequartz glass crucible as claimed in claim 13, wherein the macularcrystallized regions include unit regions each having an independentform as the marginal part thereof is substantially closed and the areaof the form falls within a range of from 10 to 100 mm².
 16. The quartzglass crucible as claimed in claim 15, wherein at least a part of theunit regions of the macular crystallized regions are further bondedcontinuously to each other.
 17. The quartz glass crucible as claimed inclaim 16, wherein in the macular crystallized regions, microholes offrom 10 to 100 μM in size are not generated during pulling ofsingle-crystal silicon.
 18. The quartz glass crucible as claimed inclaim 13, wherein the crystallization promoter is at least one 2a Groupelement selected from magnesium, strontium, calcium and barium.
 19. Thequartz glass crucible as claimed in claim 13, wherein thecrystallization promoter is barium, and the crystallizationpromoter-containing layer is formed by applying a barium-coatedhigh-purity silica powder onto the inner surface of the quartz glasscrucible and melting it thereon.
 20. The quartz glass crucible asclaimed in 19, wherein in feeding the barium-coated high-purity silicapowder onto the inner surface of the quartz glass crucible, thebarium-coated high-purity silica powder is sprayed plural times fromplural sites so that barium could be macularly distributed in the innersurface of the quartz glass crucible in accordance with the macularcrystallized regions to be formed in pulling of single-crystal silicon.21. The quartz glass crucible as claimed in claim 19, wherein thecrystallization promoter-containing layer has a thickness of from 30 to200 μm.
 22. The quartz glass crucible as claimed in claim 19, whereinthe crystallization promoter-containing layer has a barium concentrationof from 100 to 200 ppm.
 23. The quartz glass crucible as claimed inclaim 19, wherein the crystallization promoter-containing layer has abarium concentration of from 130 to 170 ppm.
 24. A method for producingsingle-crystal silicon by using the quartz glass crucible of claim 13,characterized by comprising a step of putting polycrystalline siliconinto the quartz glass crucible, a step of heating and melting thepolycrystalline silicon to form a molten silicon liquid, and a step ofpulling up single-crystal silicon from the molten silicon liquid in thequartz glass crucible by using a seed crystal.